CN104269419B - Image sensor and forming method thereof - Google Patents
Image sensor and forming method thereof Download PDFInfo
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- CN104269419B CN104269419B CN201410494217.2A CN201410494217A CN104269419B CN 104269419 B CN104269419 B CN 104269419B CN 201410494217 A CN201410494217 A CN 201410494217A CN 104269419 B CN104269419 B CN 104269419B
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Abstract
The invention discloses an image sensor and a forming method thereof. The image sensor comprises a semiconductor substrate, a photodiode array located in the semiconductor substrate, and an N-type doping area. The photodiode array comprises a plurality of rows of photodiodes arranged in parallel, and each row comprises the photodiodes which comprise N-type doping layers. The photodiode array comprises a dark area and a light sensitive area which are adjacent to each other. The dark area comprises a plurality of rows of photodiodes, and the surface of the dark area is covered with a metal layer. The N-type doping area located in the light sensitive area at least is located below the photodiodes in the row closest to the edge of the dark area and surrounds the N-type doping layers of the photodiodes in the row, and the N-type doping area is connected with the N-type doping layers. The performance of the image sensor is improved.
Description
Technical field
The present invention relates to technical field of semiconductors, particularly to a kind of imageing sensor and forming method thereof.
Background technology
Imageing sensor is the semiconductor device that optical image signal is converted to the signal of telecommunication.Image taking sensor is as pass
The product of key parts becomes the object of current and following industry concern, attracts numerous manufacturers and puts into.With product category area
Point, image sensor products are broadly divided into charge-coupled image sensor (Charge-coupled Device image
Sensor, abbreviation ccd image sensor), complementary metal oxide imageing sensor (Complementary Metal
Oxide Semiconductor image sensor, abbreviation cmos sensor).Cmos image sensor is a kind of fast-developing
Solid state image sensor, due to the image sensor portion in cmos image sensor and control circuit part be integrated in same
In chip, the therefore small volume of cmos image sensor, low in energy consumption, cheap, compared to traditional CCD (Charged Couple) figure
As sensor has more advantage, also it is more easy to popularize.
Refer to Fig. 1, Fig. 1 is the electrical block diagram of the cmos image sensor of existing 4T structure, including：Transmission
Transistor M3, row gating transistor M4 are followed in transistor M1, reset transistor M2, source.Described 4T structure C mos image sensor
Operation principle be：Transmission transistor M1 is used for for the photogenerated charge of light sensitive diode PD being transferred to floating diffusion region FD, resets
Transistor M2 is used for floating diffusion region FD is resetted, and it is defeated for amplifying the signal of telecommunication of floating diffusion region FD that transistor M3 is followed in source
Go out.Its work process includes：Control reset transistor M2 to open by reset signal R, floating diffusion region FD is set to high potential；So
Turn off reset transistor M2 afterwards, and transmission transistor M1 is opened by the control of transmission signal T, by the photoproduction electricity in light sensitive diode PD
Lotus is transferred to floating diffusion region FD, makes floating diffusion region FD produce pressure drop, and this pressure drop is followed transistor M3 by source and is expert at choosing
The outfan out output of logical transistor M4, the pressure drop of this output is output signal.
Conventional images sensor generally comprises the pel array of some pixel cell compositions, each pixel in pel array
Unit all comprises a photodiode, and photodiode converts optical signal into the signal of telecommunication, then presses picture from array for the row
Element reads the value of these signals of telecommunication.The dark space adjacent with the photosensitive area that photosensitive pixel is located can be included on conventional images sensor,
Described dark space is covered, typically with metal layers shielding, and as reference pixel, the signal of telecommunication of real image sensor output is sense to the pixel in dark space
Light pixel and reference pixel signal value process by difference channel after signal, because photosensitive pixel and reference pixel are in reality
All noise can be produced, after processing by difference channel, the signal of telecommunication of output essentially eliminates noise in start-up course, such that it is able to
Improve the accuracy of imaging.
Existing imageing sensor, when light intensity is excessive, has been filled with electronics in the potential well of photosensitive area pixel, and light intensity enters one
When step increases, superfluous electrons outwards overflow, and the pixels electron in the photosensitive area adjacent with dark space can enter dark space after overflowing
Interior, the output signal of the reference pixel of impact dark space, thus affecting the accuracy of final image sensor output signal, serious shadow
Ring the performance of imageing sensor.
Content of the invention
The problem that the present invention solves is to provide a kind of imageing sensor and forming method thereof, can improve imageing sensor
Performance.
For solving the above problems, the present invention provides a kind of imageing sensor, including：Semiconductor substrate；Positioned at quasiconductor lining
Photodiode array in bottom, described photodiode array includes several rows photodiode arranged in parallel, described light
Electric diode includes n-type doping layer；Described photodiode array includes dark space and photosensitive area, described dark space and photosensitive area phase
Neighbour, includes several rows photodiode in described dark space, and described dark space surface is coated with metal level；N in photosensitive area
Type doped region, described n-type doping area is located at least in closest to below a line photodiode of dark space edge and surrounds this row
Photodiode n-type doping layer, described n-type doping area is connected with n-type doping floor.
Optionally, described image sensor includes pixel unit array, and each pixel cell includes photoelectricity two pole respectively
Pipe.
Optionally, also include：N-type in dark space, below the photodiode of at least a line of photosensitive area edge
Heavily doped layer, described n-type doping area surrounds the n-type doping floor of photodiode.
Optionally, include N row photodiode arranged in parallel in dark space, described dark from photosensitive area sensing dark space direction
There is below some adjacent or photodiode of spaced rows in N/2 row in area n-type doping area, described n-type doping area bag
Enclose the n-type doping layer of photodiode.
Optionally, the doping content of the n-type doping layer of described photodiode is 2E15atom/cm3～1E18atom/
cm3, the doping content in described n-type doping area is 5E15atom/cm3～5E18atom/cm3.
Optionally, the doping depth in described n-type doping area is 0.5 μm～3 μm.
Optionally, also include：P-type pinning layer positioned at the n-type doping layer surface of photodiode.
Optionally, the n-type doping area below the photodiode of same a line is continuous doped region.
Optionally, the n-type doping area below the photodiode of same a line is some discrete doped regions.
Optionally, also include：Described n-type doping area surface has metal interconnection structure.
Optionally, the length in described n-type doping area is more than the length of diode array row, and part n-type doping area is located at two
Pole pipe array external.
Optionally, the part n-type doping area surface outside positioned at diode array has metal interconnection structure.
Optionally, described n-type doping area connects positive potential.
Optionally, the scope of described positive potential is 0.5V～3V.
For solving the above problems, technical scheme also proposes a kind of forming method of imageing sensor, including：Carry
For Semiconductor substrate；Form photodiode array in described Semiconductor substrate, described photodiode array includes some
Row photodiode arranged in parallel, described photodiode includes n-type doping layer, and described photodiode array includes dark space
And photosensitive area, described dark space and photosensitive area adjacent；Form n-type doping area in photosensitive area, described n-type doping area is located at least in
Below a line photodiode of dark space edge and surround this row photodiode n-type doping layer, described N-type
Doped region is connected with n-type doping layer；In described dark space forming metal layer on surface.
Optionally, described n-type doping area is formed using ion implantation technology.
Optionally, after forming described n-type doping area, re-form photodiode in described photodiode array
N-type doping layer.
Optionally, also include：In dark space, the photodiode N-type formed below of at least a line of photosensitive area edge
Heavily doped layer, described n-type doping area surrounds the n-type doping floor of photodiode.
Optionally, include N row photodiode arranged in parallel in dark space, described dark from photosensitive area sensing dark space direction
Some adjacent or spaced rows photodiode n-type doping area formed below in N/2 row in area, described n-type doping area bag
Enclose the n-type doping layer of photodiode.
Optionally, the doping content of the n-type doping layer of described photodiode is 2E15atom/cm3～1E18atom/
cm3, the doping content in described n-type doping area is 5E15atom/cm3～5E18atom/cm3.
Optionally, the doping depth in described n-type doping area is 0.5 μm～3 μm.
Optionally, also include：Form p-type pinning layer in the n-type doping layer surface of described photodiode.
Optionally, positioned at the n-type doping area of same a line be continuous doped region.
Optionally, the n-type doping area positioned at same a line is some discrete doped regions.
Optionally, also include：Also include：Form metal interconnection structure on described n-type doping area surface.
Optionally, the length in described n-type doping area is more than the length of diode array row, and part n-type doping area is located at two
Pole pipe array external.
Optionally, the part n-type doping area surface outside positioned at diode array forms metal interconnection structure.
Optionally, described n-type doping area is connected with positive potential.
Optionally, the scope of described positive potential is 0.5V～3V.
Compared with prior art, technical scheme has advantages below：
In technical scheme, described image sensor includes：Photodiode array, described photodiode battle array
Row include including several rows photodiode in dark space described in dark space and photosensitive area, and described dark space surface is coated with metal level；
N-type doping area in photosensitive area, described n-type doping area is located at least in a line photodiode closest to dark space edge
Lower section and surround this row photodiode n-type doping layer, described n-type doping area is connected with n-type doping floor.Described N-type is mixed
Miscellaneous area can absorb the spilling electronics in photosensitive area to dark space diffusion, it is to avoid the spilling electronics in photosensitive area enters shadow in dark space
Ring the output signal value of the pixel cell in described dark space I.The N of the photodiode of described n-type doping area and other adjacent lines
Type doped region is isolated.And, the described spilling electronics that can also absorb in photosensitive area internal migration, it is to avoid exist due to overflowing electronics
Migration in different pixels unit, the exact value of the optical signal of photosensitive pixel output in impact photosensitive area, such that it is able to avoid
Overflow the halation phenomenon that electronics causes output image.
Further, described n-type doping area surface has metal interconnection structure, can apply on described metal interconnection structure
Plus positive potential, thus in time systemic for described n-type doping area electronics is derived, it is to avoid described n-type doping area absorbs electronics mistake
Many and overflow, spread in photosensitive area, and diffuse in dark space, affect the performance of imageing sensor.
Further, described n-type doping area part is located at outside photodiode array.Due to described image sensor
Integrated level is typically higher, and the spacing between adjacent photodiode is less, the n-type doping area in described photodiode array
The size of the metal interconnection structure that surface is formed is less, easily causes the company between described metal interconnection structure and n-type doping area
Connect unstable.And the area being located at the part n-type doping area outside described photodiode array region can be larger, described metal
The part n-type doping area surface that interconnection structure is located at outside described photodiode array region, it is easy to be formed, can be improved described
Quality of connection between the quality of metal interconnection structure and described metal interconnection structure and n-type doping area.
Technical scheme also provides a kind of forming method of imageing sensor, forms photoelectricity on a semiconductor substrate
Diode array, described photodiode array includes dark space and photosensitive area；Form n-type doping area, described N-type in photosensitive area
Doped region be located at least in closest to below a line photodiode of dark space edge and surround this row photodiode N
Type doped layer.Described n-type doping area can absorb the spilling electronics in photosensitive area to dark space diffusion, it is to avoid the spilling in photosensitive area
Electronics enters in dark space affects the output signal value of the pixel cell in described dark space I.Described n-type doping area is adjacent with other
Row photodiode n-type doping separate from.And, the described spilling electronics that can also absorb in photosensitive area internal migration,
Avoid due to overflowing migration in different pixels unit for the electronics, the standard of the optical signal of photosensitive pixel output in impact photosensitive area
Really it is worth, such that it is able to avoid overflowing the halation phenomenon that electronics causes output image.
Brief description
Fig. 1 is the electrical block diagram of the imageing sensor of the prior art of the present invention；
Fig. 2 to Fig. 6 is the structural representation of the imageing sensor of embodiments of the invention；
Fig. 7 is the structural representation of the forming process of the imageing sensor of embodiments of the invention.
Specific embodiment
As described in the background art, the performance of existing imageing sensor needs further to be improved.
Because electronics is spilled over to dark space in the pixel of photosensitive area, dark space noise in output signal is led to change, thus shadow
Ring the performance of final image sensor.
Photodiode n-type doping formed below in embodiments of the invention, at dark space with photosensitive area boundary position
Area, and described n-type doping area surrounds the n-type doping floor of described photodiode, makes the electronics quilt of effusion in described n-type doping layer
Described n-type doping area collects, thus avoiding overflowing in electronics entrance dark space, thus improving the performance of the imageing sensor of formation.
Understandable for enabling the above objects, features and advantages of the present invention to become apparent from, below in conjunction with the accompanying drawings to the present invention
Specific embodiment be described in detail.
Refer to Fig. 2 and Fig. 3, be the structural representation of the imageing sensor of the present embodiment.Fig. 3 is the secant AA ' along along Fig. 2
Generalized section.
Described image sensor includes：Semiconductor substrate 100；Some discrete in described Semiconductor substrate 100
The photodiode array that photodiode 101 is constituted.Described image sensor can be back side illumination image sensor (BSI) or
Front illuminated image sensor (FSI).Described photodiode array includes dark space I and photosensitive area II, described dark space I and photosensitive area
II is adjacent, includes several rows photodiode 101, and described dark space I surface is coated with metal level 200 in described dark space I.Described
Imageing sensor also includes the n-type doping area 110 in the II of photosensitive area, and described n-type doping area is located at least in closest to dark space
A line photodiode 102 lower section of edge and surround this row photodiode n-type doping layer.
Specifically, described Semiconductor substrate 100 is used for being formed device architecture or chip circuit, described Semiconductor substrate 100
Material include the semi-conducting materials such as silicon, germanium, SiGe, GaAs, described Semiconductor substrate 100 can be that body material can also
It is composite construction such as silicon-on-insulator.Those skilled in the art can be according to the semiconductor device being formed in Semiconductor substrate 100
Part selects the type of described Semiconductor substrate 100, and the type of therefore described Semiconductor substrate should not limit the protection model of the present invention
Enclose.
The extension that described Semiconductor substrate 100 can also include substrate and be formed at substrate surface by epitaxy technique
Layer, described substrate thicker, doping content is larger, and defect is a lot；And general only several microns of the epitaxial layer of substrate surface, doping
Concentration is relatively low, and defect is little.In described photodiode 101 formation and described epitaxial layer.Additionally, described Semiconductor substrate 100
Interior can also have well region.The monocrystalline silicon layer that described epitaxial layer adulterates for p-type.
Described photodiode 101 can produce photo-generated carrier in the case of being excited by extraneous light intensity, i.e. electricity
Son.Described photodiode 101 can be formed by ion implantation technology, and, by controlling the energy of ion implanting and dense
Degree, can control depth and the injection scope of ion implanting, thus controlling depth and the thickness of photodiode 101.
In the present embodiment, described photodiode 101 includes n-type doping layer, and the dopant ion of described n-type doping layer includes
One or more of phosphonium ion, arsenic ion or antimony ion n-type doping ion.Described photodiode 101 is as image sensing
The light-sensitive device of the pixel cell of device, remains carrier for producing light.Described photodiode 101 is in Semiconductor substrate 100
According to matrix form arrangement.
Can also be by well region or fleet plough groove isolation structure isolation between adjacent photodiode 101.Described quasiconductor
Substrate 100 includes pixel unit array, and described photodiode 101 is as a part for the pixel cell of imageing sensor, institute
State pixel cell also include in the Semiconductor substrate 100 around photodiode 101 for obtaining and exporting the signal of telecommunication
Image element circuit, follow transistor, row gating transistor etc. including transmission transistor, reset transistor, source.
In the present embodiment, described n-type doping area 110 is located at a line photodiode in the II of photosensitive area closest to dark space I
In the Semiconductor substrate 100 of 101 lower sections.Refer to Fig. 3, be the generalized section of the secant AA along along Fig. 2.
Described n-type doping area 110 surrounds side wall and the bottom of described photodiode 101, and described n-type doping area 110
Doping content be more than described photodiode 101 n-type doping layer doping content.In the present embodiment, described n-type doping layer
Doping content be 2E15atom/cm3～1E18atom/cm3, the doping content in described n-type doping area 110 is 5E15atom/
cm3～5E18atom/cm3.The doping content in described n-type doping area 110 can be more than or less than the doping of described n-type doping floor
Concentration.Described n-type doping area can absorb the spilling electronics in the II of photosensitive area to dark space I diffusion, it is to avoid overflowing in the II of photosensitive area
Going out in electronics entrance dark space I affects the output signal value of the pixel cell in described dark space I.In the present embodiment, described N-type is mixed
The doping content in miscellaneous area is more than the doping content of n-type doping floor, is more easy to absorb and overflows electronics.Described n-type doping area and other phases
The n-type doping of the photodiode 101 of adjacent rows separate from.
The doping depth in described n-type doping area 110 is 0.5 μm～3 μm, described doping depth larger such that it is able to as far as possible
Increase the absorbability to electronics, Semiconductor substrate 100 internal diffusion reducing electronics from n-type doping area 110 lower section is to dark space I's
Overflow electronics.
Described lower section has the photodiode 101 in n-type doping area 110, subsequently in imageing sensor work process, no
Export effective signal of telecommunication again, be only used as isolating pixel, the spilling electrons spread in other pixel cells of isolation photosensitive area II is entered
Enter in the I of dark space.Meanwhile, described n-type doping area 110 can also absorb the spilling electronics in photosensitive area II internal migration, it is to avoid by
In overflowing migration in different pixels unit for the electronics, affect the accurate of the optical signal that the photosensitive pixel in the II of photosensitive area exports
Value, such that it is able to avoid overflowing the halation phenomenon that electronics causes output image.
In other embodiments of the invention, the photoelectricity two of a line in the close dark space I in the II of photosensitive area or a few row
Can all have n-type doping area below pole pipe, such that it is able to improve the quantity in n-type doping area, improve to overflowing in the II of photosensitive area
Go out the absorbability of electronics.
In other embodiments of the invention, in the dark space I of described image sensor, it is located at photosensitive area II edge extremely
Also there is below the photodiode 101 of few a line N-type heavily doped layer 110, described n-type doping area 110 surrounds photodiode
N-type doping layer.Below a line in described dark space I or a few row photodiode 101, also there is described N-type heavily doped layer 110,
The spilling electronics not absorbed by the n-type doping area 110 in the II of photosensitive area can be absorbed further, it is to avoid remaining spilling electronics continues
Continue and diffuse in the photodiode 101 of other row in the I of dark space.N-type heavily doped layer 110 in described dark space I, generally proximate to
Photosensitive area, on the one hand can absorb the spilling electronics diffusing to dark space I from photosensitive area II in time, on the other hand it can be ensured that dark
Area I has the photodiode 101 gone enough to constitute sufficient amount of reference pixel.
In one embodiment of the invention, there is N row photodiode arranged in parallel 101, from sense in described dark space I
Below the several rows photodiode 101 in N/2 row in the described dark space I in light area II sensing dark space I direction, there is n-type doping
Area 110, described n-type doping area 100 surrounds the n-type doping floor of photodiode 101.The photodiode 101 of described several rows
It can be the photodiode in adjacent lines of pixels or spaced pixel column.
Refer to Fig. 4, be the generalized section of the secant BB ' along along Fig. 2.
In the present embodiment, described n-type doping area 110 is continuous doped region, in the photosensitive area II of dark space I edge
A full line photodiode 101 below.Described n-type doping area 110 can as a complete spilling Electron absorption region,
As the electrons spread barrier zones between dark space I and photosensitive area II.
In other embodiments of the invention, described n-type doping area 110 is some discrete doped regions, refer to Fig. 5,
Generalized section for the imageing sensor of one embodiment of the present of invention.
Mutually discrete between the n-type doping area 110 of different photodiodes 101 lower section in same pixel column, be
Multiple discontinuous doped regions.Each photodiode 101 corresponds to a n-type doping area 110.
The electronics being produced by illumination due to the photodiode 101 that surrounded by described n-type doping area 110 is all by described N
Type doped region 110 absorbs, thus the described photodiode 101 being surrounded by n-type doping area 110 is all as inactive pixels.
Described n-type doping area 110 can be connected with positive potential, thus in time by systemic for described n-type doping area 110 electricity
Son is derived, it is to avoid described n-type doping area 110 absorbs electronics and excessively overflows, and spreads, and diffuse in the II of photosensitive area
In the I of dark space, the performance of impact imageing sensor.In one embodiment of the invention, the scope of described positive potential be 0.5V～
3V.In the present embodiment, described n-type doping area 110 surface also has metal interconnection structure, by described metal interconnection structure by institute
State n-type doping area 110 to be connected with circuit.
In the present embodiment, described n-type doping area 110 is located in described photodiode array, described n-type doping area
110 surface has one or more metal plug structures, is connected with the circuit being subsequently formed by described metal plug structure.
Refer to Fig. 6, in other embodiments of the invention, the length in described n-type doping area 110 can be more than photoelectricity two
The length of pole pipe array row, part n-type doping area 100 is located at outside photodiode array.
Because the integrated level of described image sensor is typically higher, the spacing between adjacent photodiode 101 is less, this
In embodiment, directly n-type doping area 110 surface in described photodiode array forms the difficulty of metal interconnection structure relatively
Greatly.In other embodiments of the invention, described Semiconductor substrate 100 also include outer outside photodiode array region
Enclose region, partly described n-type doping area 110 is located in described outer peripheral areas.Outside described photodiode array region
The area in part n-type doping area 110 can be larger, and described metal interconnection structure is located at outside described photodiode array region
The quality of described metal interconnection structure, it is easy to be formed, can be improved in part n-type doping area 110 surface.It is located at described photoelectricity simultaneously
Part n-type doping area 110 outside diode array region simultaneously can also be used as the outer peripheral areas in described Semiconductor substrate 100
Interior N trap.
In other embodiments of the present invention, described image sensor can also include mixing positioned at the N-type of photodiode 101
The p-type pinning layer on diamicton surface, described p-type pinning layer has fixing surface potential it is impossible to absorb photon, produces carrier,
Such that it is able to be incident illumination completely into photodiode 101 inside, and do not affected by configuration of surface.
Top, described metal level 200 and quasiconductor that the metal level 200 on described dark space I surface is located on described dark space I
Also there is between substrate 100 other transistor arrangements of pixel cell, such as transmission transistor, reset transistor or row gating
Transistor etc, and be connected with above-mentioned transistor arrangement metal interconnection structure, be located at described metal level 200 and quasiconductor lining
Interlayer dielectric layer between bottom 100 etc..
In embodiments of the invention, also provide a kind of forming method of above-mentioned imageing sensor.
Specifically, refer to Fig. 7, Semiconductor substrate 100 is provided, form photoelectricity two pole in described Semiconductor substrate 100
Pipe array, described photodiode array includes several rows photodiode arranged in parallel 101, and every a line includes some photoelectricity
Diode 101, described photodiode 101 includes n-type doping layer, and described photodiode array includes dark space I and photosensitive area
II, described dark space I and photosensitive area II is adjacent；Form n-type doping area 110 in the II of photosensitive area, described n-type doping area 110 is at least
The N-type of a line photodiode 101 lower section and the photodiode 101 surrounding this row that are located nearest to dark space edge is mixed
Diamicton, the doping content in described n-type doping area 110 is more than the doping content of n-type doping floor and described n-type doping area is mixed with N-type
Diamicton connects.
Specifically, described Semiconductor substrate 100 is used for being formed device architecture or chip circuit, described Semiconductor substrate 100
Material include the semi-conducting materials such as silicon, germanium, SiGe, GaAs, described Semiconductor substrate 100 can be that body material can also
It is composite construction such as silicon-on-insulator.Those skilled in the art can be according to the semiconductor device being formed in Semiconductor substrate 100
Part selects the type of described Semiconductor substrate 100, and the type of therefore described Semiconductor substrate should not limit the protection model of the present invention
Enclose.
Described Semiconductor substrate 100 can also be including substrate and is formed at the outer of substrate surface by epitaxy technique
Prolong layer, described substrate thicker, doping content is larger, and defect is a lot；And general only several microns of the epitaxial layer of substrate surface, mix
Miscellaneous concentration is relatively low, and defect is little.In described photodiode 101 formation and described epitaxial layer.Additionally, described Semiconductor substrate
Can also have well region in 100.The monocrystalline silicon layer that described epitaxial layer adulterates for p-type.
In the present embodiment, the monocrystal silicon that described Semiconductor substrate 100 is adulterated for p-type, have in described Semiconductor substrate 100
P-well.
In the present embodiment, first in the photosensitive area II of described Semiconductor substrate 100, it is located at dark space I edge formation N-type
Doped region 110, then, re-forms described photodiode 102.
The forming method in described n-type doping area 110 includes：Form pattern mask on described Semiconductor substrate 100 surface
Layer, described Patterned masking layer exposes the part semiconductor substrate 100 in n-type doping area to be formed；With described pattern mask
Layer is mask, carries out N-type ion implanting to described Semiconductor substrate 100, forms n-type doping area in Semiconductor substrate 100
110.By controlling the energy of described N-type ion implanting and dosage, the depth in n-type doping area 110 of formation and dense can be controlled
Degree.
After forming described n-type doping area 110, remove described Patterned masking layer, shape in described Semiconductor substrate 100
Become mask layer, described mask layer defines the positions and dimensions of photoelectric diode 101, with described mask layer as mask, to described half
Conductor substrate 100 carries out ion implanting, forms the doped layer contrary with Semiconductor substrate 100 doping type, as photoelectricity two pole
Pipe 101, then removes described mask layer.Described photodiode 101 arranges according to array, forms photodiode array.If
Dry row photodiode arranged in parallel 101 is located in the I of dark space, and several rows photodiode arranged in parallel 101 is located at photosensitive
In area II, and a line photodiode 101 closest to dark space I is located in described n-type doping area 110.By controlling ion note
The energy entering and concentration, can control ion implanting depth and injection scope, thus control photodiode 101 depth and
Thickness.
In the present embodiment, described photodiode 101 includes n-type doping layer, and the doping content of described n-type doping layer is
2E15atom/cm3～1E18atom/cm3, the doping content in described n-type doping area 110 is 5E15atom/cm3～5E18atom/
cm3.Described n-type doping area can absorb the spilling electronics in the II of photosensitive area to dark space I diffusion, it is to avoid the spilling in the II of photosensitive area
Electronics enters in the I of dark space affects the output signal value of the pixel cell in described dark space I.The doping in described n-type doping area 110
Concentration can be more than or less than the doping content of described n-type doping layer.In the present embodiment, the doping content in described n-type doping area
More than the doping content of n-type doping layer, it is more easy to absorb and overflows electronics.
The doping depth in described n-type doping area 110 is 0.5 μm～3 μm, described doping depth larger such that it is able to as far as possible
Increase the absorbability to electronics, Semiconductor substrate 100 internal diffusion reducing electronics from n-type doping area 110 lower section is to dark space I's
Overflow electronics.
In other embodiments of the invention it is also possible to after forming described photodiode 101 array, re-form institute
State n-type doping area 110.
In other embodiments of the invention, can a line in the close dark space I in the II of photosensitive area or a few row light
All form n-type doping area below electric diode, such that it is able to improve the quantity in n-type doping area, improve to overflowing in the II of photosensitive area
Go out the absorbability of electronics.
In other embodiments of the invention, except being located at a line or the multirow photoelectricity of dark space I edge in photosensitive area II
Outside diode n-type doping formed below area 110, can also be in the I of dark space, the photoelectricity of at least a line of photosensitive area II edge
Also form described N-type heavily doped layer 110, described n-type doping area 100 also surrounds the photoelectricity in described dark space I below diode 101
The n-type doping layer of diode 101.Below a line in described dark space I or a few row photodiode 101, also there is described N-type weight
Doped layer 110, can absorb the spilling electronics not absorbed by the n-type doping area 110 in the II of photosensitive area, it is to avoid remaining further
Overflow in the photodiode 101 that electronics continues diffuse to other row in the I of dark space.N-type heavily doped layer in described dark space I
110, generally proximate to photosensitive area, the spilling electronics diffusing to dark space I from photosensitive area II, the opposing party on the one hand can be absorbed in time
Face is it can be ensured that dark space I has the photodiode 101 gone enough to constitute sufficient amount of reference pixel.
Specifically, in one embodiment of the invention, include N row photodiode arranged in parallel in described dark space I
101, point to dark space I direction, the photoelectricity two of some adjacent or spaced rows in the N/2 row in described dark space I from photosensitive area II
Also form n-type doping area 110, described n-type doping area 110 surrounds the n-type doping floor of photodiode below pole pipe 101.Described
The photodiode 101 of several rows can be the photodiode in adjacent lines of pixels or spaced pixel column.
Described lower section has the photodiode 101 in n-type doping area 110, subsequently in imageing sensor work process, no
Export effective signal of telecommunication again, be only used as isolating pixel, the spilling electrons spread in other pixel cells of isolation photosensitive area II is entered
Enter in the I of dark space.Meanwhile, described n-type doping area 110 can also absorb the spilling electronics in photosensitive area II internal migration, it is to avoid by
In overflowing migration in different pixels unit for the electronics, affect the accurate of the optical signal that the photosensitive pixel in the II of photosensitive area exports
Value, such that it is able to avoid overflowing the halation phenomenon that electronics causes output image.
In the present embodiment, described n-type doping area 110 is continuous doped region, in the photosensitive area II of dark space I edge
A full line photodiode 101 below.Described n-type doping area 110 can as a complete spilling Electron absorption region,
As the electrons spread barrier zones between dark space I and photosensitive area II.
In other embodiments of the invention, described n-type doping area 110 is some discrete doped regions, positioned at same picture
Mutually discrete between the n-type doping area 110 of different photodiodes 101 lower section in plain row, it is multiple discontinuous doped region.
Each photodiode 101 corresponds to a n-type doping area 110.
The electronics being produced by illumination due to the photodiode 101 that surrounded by described n-type doping area 110 is all by described N
Type doped region 110 absorbs, thus the described photodiode 101 being surrounded by n-type doping area 110 is all as inactive pixels.
In the present embodiment, after forming described photodiode 101, can also be on described photodiode 101 surface
Form p-type pinning layer.P-type ion implanting is carried out to the n-type doping layer surface of photodiode 101, forms p-type pinning layer.
In the present embodiment, subsequently can also form metal interconnection structure on described n-type doping area 110 surface, by described
Described n-type doping area 110 is connected by metal interconnection structure with circuit.Positive potential can be applied on described metal interconnection structure,
Thus in time systemic for described n-type doping area 110 electronics is derived, it is to avoid described n-type doping area 110 absorb electronics excessive and
Overflow, spread in the II of photosensitive area, and diffuse in the I of dark space, the performance of impact imageing sensor.
Positive potential can be applied in described n-type doping area 110, thus in time will be systemic for described n-type doping area 110
Electronics is derived, it is to avoid described n-type doping area 110 absorbs electronics and excessively overflows, and spreads in the II of photosensitive area, and diffusion
To the I of dark space, the performance of impact imageing sensor.In one embodiment of the invention, the scope of described positive potential is 0.5V
～3V.In the present embodiment, described n-type doping area 110 is located in described photodiode array, described n-type doping area 110
Surface has one or more metal plug structures, is connected with the circuit being subsequently formed by described metal plug structure, and,
Positive potential is applied to described n-type doping area 110 by described metal plug structure.
In other embodiments of the invention, the length in described n-type doping area 110 can be more than photodiode array row
Length, part n-type doping area 100 be located at photodiode array outside.Because the integrated level of described image sensor is general
Higher, the spacing between adjacent photodiode 101 is less, in the present embodiment, the directly N in described photodiode array
The difficulty that type doped region 110 surface forms metal interconnection structure is larger, easily causes metal interconnection structure and n-type doping area 110
Between switching performance unstable.
In other embodiments of the invention, described Semiconductor substrate 100 is also included positioned at photodiode array region
Outer outer peripheral areas, partly described n-type doping area 110 is in described outer peripheral areas.Positioned at described photodiode array area
The area in overseas part n-type doping area 110 can be larger, and described metal interconnection structure is located at described photodiode array area
The quality of described metal interconnection structure, it is easy to be formed, can be improved in overseas part n-type doping area 110 surface.It is located at institute simultaneously
The part n-type doping area 110 stating outside photodiode array region simultaneously can also be used as outer in described Semiconductor substrate 100
Enclose the N trap in region.
Refer to Fig. 2, metal level 200 is formed on described dark space I.
Before forming metal level 200, need to form other crystal of pixel cell on described Semiconductor substrate 100 surface
Tubular construction, such as transmission transistor, reset transistor or row gating transistor etc, and cover Semiconductor substrate 100 with
And the inter-level dielectric Rotating fields of above-mentioned transistor, the metal of connection transistor being located in described inter-level dielectric Rotating fields mutually link
Structure.
Finally form metal level 200 at described dark space I top, described metal level 200 covers whole dark space I.
To sum up, in the forming method of the imageing sensor of the present embodiment, n-type doping area, described N-type are formed in photosensitive area
Doped region be located at least in closest to below a line photodiode of dark space edge and surround this row photodiode N
Type doped layer.Described n-type doping area can absorb the spilling electronics in photosensitive area to dark space diffusion, it is to avoid the spilling in photosensitive area
Electronics enters in dark space affects the output signal value of the pixel cell in described dark space I.Described n-type doping area is adjacent with other
Row photodiode n-type doping separate from.And, the described spilling electronics that can also absorb in photosensitive area internal migration,
Avoid due to overflowing migration in different pixels unit for the electronics, the standard of the optical signal of photosensitive pixel output in impact photosensitive area
Really it is worth, such that it is able to avoid overflowing the halation phenomenon that electronics causes output image.
Although present disclosure is as above, the present invention is not limited to this.Any those skilled in the art, without departing from this
In the spirit and scope of invention, all can make various changes or modifications, therefore protection scope of the present invention should be with claim institute
The scope limiting is defined.
Claims (29)
1. a kind of imageing sensor is it is characterised in that include：
Semiconductor substrate；
Photodiode array in Semiconductor substrate, described photodiode array includes several rows light arranged in parallel
Electric diode, described photodiode includes n-type doping layer；
Described photodiode array includes dark space and photosensitive area, and described dark space and photosensitive area are adjacent, if including in described dark space
Dry row photodiode, and described dark space surface is coated with metal level；
N-type doping area in photosensitive area, described n-type doping area is located at least in a line photoelectricity two closest to dark space edge
Below pole pipe and surround this row photodiode n-type doping layer, described n-type doping area is connected with n-type doping floor.
2. imageing sensor according to claim 1 is it is characterised in that described image sensor includes pixel cell battle array
Row, each pixel cell includes photodiode respectively.
3. imageing sensor according to claim 1 is it is characterised in that described n-type doping area is in dark space, photosensitive area
Below the photodiode of at least a line of edge, described n-type doping area surrounds the n-type doping floor of photodiode.
4. imageing sensor according to claim 3 is it is characterised in that include N row photoelectricity two arranged in parallel in dark space
Pole pipe, the photodiode of some adjacent or spaced rows in the N/2 row in the described dark space in photosensitive area sensing dark space direction
Lower section has n-type doping area, and described n-type doping area surrounds the n-type doping floor of photodiode.
5. the imageing sensor according to claim 1 or 3 is it is characterised in that the n-type doping layer of described photodiode
Doping content is 2E15atom/cm3～1E18atom/cm3, the doping content in described n-type doping area is 5E15atom/cm3~
5E18atom/cm3.
6. the imageing sensor according to claim 1 or 3 is it is characterised in that the doping depth in described n-type doping area is
0.5 μm～3 μm.
7. imageing sensor according to claim 1 is it is characterised in that also include：N-type doping positioned at photodiode
The p-type pinning layer of layer surface.
8. the imageing sensor according to claim 1 or 3 is it is characterised in that be located at below with the photodiode of a line
N-type doping area be continuous doped region.
9. the imageing sensor according to claim 1 or 3 is it is characterised in that be located at below with the photodiode of a line
N-type doping area be some discrete doped regions.
10. the imageing sensor according to claim 1 or 3 is it is characterised in that also include：Described n-type doping area surface has
There is metal interconnection structure.
11. imageing sensors according to claim 1 or 3 are it is characterised in that the length in described n-type doping area is more than two
The length of pole pipe array row, part n-type doping area is located at outside diode array.
12. imageing sensors according to claim 11 are it is characterised in that be located at the part N-type outside diode array
Doped region surface has metal interconnection structure.
13. imageing sensors according to claim 1 are it is characterised in that described n-type doping area connects positive potential.
14. imageing sensors according to claim 13 are it is characterised in that the scope of described positive potential is 0.5V～3V.
A kind of 15. forming methods of imageing sensor are it is characterised in that include：
Semiconductor substrate is provided；
Form photodiode array in described Semiconductor substrate, it is arranged in parallel that described photodiode array includes several rows
Photodiode, described photodiode includes n-type doping layer, and described photodiode array includes dark space and photosensitive area,
Described dark space and photosensitive area are adjacent；
Form n-type doping area in photosensitive area, described n-type doping area is located at least in a line photoelectricity two closest to dark space edge
Below pole pipe and surround this row photodiode n-type doping layer, described n-type doping area is connected with n-type doping floor；
In described dark space forming metal layer on surface.
The forming method of 16. imageing sensors according to claim 15 is it is characterised in that adopt ion implantation technology shape
Become described n-type doping area.
The forming method of 17. imageing sensors according to claim 15 is it is characterised in that form described n-type doping area
Afterwards, re-form the n-type doping layer of the photodiode in described photodiode array.
The forming method of 18. imageing sensors according to claim 15 is it is characterised in that also include：In dark space, sense
The photodiode described n-type doping area formed below of at least a line at light area edge, described n-type doping area surrounds photoelectricity two
The n-type doping layer of pole pipe.
The forming method of 19. imageing sensors according to claim 18 is it is characterised in that to include N row in dark space parallel
The photodiode of arrangement, some adjacent or spaced rows in the N/2 row in the described dark space in photosensitive area sensing dark space direction
Photodiode n-type doping formed below area, described n-type doping area surrounds the n-type doping floor of photodiode.
The forming method of 20. imageing sensors according to claim 15 or 18 is it is characterised in that described photodiode
N-type doping layer doping content be 2E15atom/cm3～1E18atom/cm3, the doping content in described n-type doping area is
5E15atom/cm3～5E18atom/cm3.
The forming method of 21. imageing sensors according to claim 15 or 18 is it is characterised in that described n-type doping area
Doping depth be 0.5 μm～3 μm.
The forming method of 22. imageing sensors according to claim 15 is it is characterised in that also include：In described photoelectricity
The n-type doping layer surface of diode forms p-type pinning layer.
The forming method of 23. imageing sensors according to claim 15 or 18 is it is characterised in that be located at the N with a line
Type doped region is continuous doped region.
The forming method of 24. imageing sensors according to claim 15 or 18 is it is characterised in that be located at the N with a line
Type doped region is some discrete doped regions.
The forming method of 25. imageing sensors according to claim 15 or 18 is it is characterised in that also include：Also include：
Form metal interconnection structure on described n-type doping area surface.
The forming method of 26. imageing sensors according to claim 15 or 18 is it is characterised in that described n-type doping area
Length be more than diode array row length, part n-type doping area be located at diode array outside.
The forming method of 27. imageing sensors according to claim 26 is it is characterised in that outside diode array
The part n-type doping area surface in portion forms metal interconnection structure.
The forming method of 28. imageing sensors according to claim 15 it is characterised in that by described n-type doping area with
Positive potential connects.
The forming method of 29. imageing sensors according to claim 28 is it is characterised in that the scope of described positive potential is
0.5V～3V.
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